// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_PROFILER_TRACKED_TIME_H_
#define BASE_PROFILER_TRACKED_TIME_H_

#include <stdint.h>

#include "base/base_export.h"
#include "base/time/time.h"

namespace tracked_objects {

//------------------------------------------------------------------------------

// TimeTicks maintains a wasteful 64 bits of data (we need less than 32), and on
// windows, a 64 bit timer is expensive to even obtain. We use a simple
// millisecond counter for most of our time values, as well as millisecond units
// of duration between those values.  This means we can only handle durations
// up to 49 days (range), or 24 days (non-negative time durations).
// We only define enough methods to service the needs of the tracking classes,
// and our interfaces are modeled after what TimeTicks and TimeDelta use (so we
// can swap them into place if we want to use the "real" classes).

class BASE_EXPORT Duration { // Similar to base::TimeDelta.
public:
    Duration();

    Duration& operator+=(const Duration& other);
    Duration operator+(const Duration& other) const;

    bool operator==(const Duration& other) const;
    bool operator!=(const Duration& other) const;
    bool operator>(const Duration& other) const;

    static Duration FromMilliseconds(int ms);

    int32_t InMilliseconds() const;

private:
    friend class TrackedTime;
    explicit Duration(int32_t duration);

    // Internal time is stored directly in milliseconds.
    int32_t ms_;
};

class BASE_EXPORT TrackedTime { // Similar to base::TimeTicks.
public:
    TrackedTime();
    explicit TrackedTime(const base::TimeTicks& time);

    static TrackedTime Now();
    Duration operator-(const TrackedTime& other) const;
    TrackedTime operator+(const Duration& other) const;
    bool is_null() const;

    static TrackedTime FromMilliseconds(int32_t ms) { return TrackedTime(ms); }

private:
    friend class Duration;
    explicit TrackedTime(int32_t ms);

    // Internal duration is stored directly in milliseconds.
    uint32_t ms_;
};

} // namespace tracked_objects

#endif // BASE_PROFILER_TRACKED_TIME_H_
